@article{TM_1975_136_a6,
     author = {A. D. Donkov and V. G. Kadyshevskii and M. D. Mateev and R. M. Mir-Kassimov},
     title = {Extension of the $S$-matrix off the mass shell and momentum space of constant curvature},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {85--129},
     publisher = {mathdoc},
     volume = {136},
     year = {1975},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TM_1975_136_a6/}
}